Friday, October 25, 2013

The adaptive immune response is the branch of our immune
system that most people are familiar with. It’s the reason vaccines work. When
exposed to a molecule that triggers an immune reaction (known as an “antigen”),
the body produces antibodies that specifically bind to that molecule,
eventually leading to its destruction. The most common class of antibody
produced is called immunoglobulin G (IgG).

Our bodies can also produce a less common type of antibody
called immunoglobulin E (IgE). Notably, IgE helps fight off parasitic
infections, but other than that, its role is largely unknown. In the developed
world, parasites are no longer a major concern, so immunologists believe that
IgE occupies its time by causing trouble, instead.

If you have allergies, blame IgE. For some reason, benign
substances such as peanuts and cat hair can incite our immune system, which
kicks out gobs of IgE. These antibodies then bind to an immune cell called a
mast cell, triggering it to release a bunch of chemicals which produce all the
symptoms we commonly associate with allergies — sneezing, coughing, itchiness
and overall misery. In worst case scenarios, an out-of-control allergic
response called anaphylatic shock occurs. This can be deadly.

Does IgE have any modern-day redemptive qualities? According
to new research in the journal Immunity, the answer is yes.

Immunologists first primed mice with various doses of bee
venom, but we will restrict our discussion to the 100- and 200-ug doses. (100
ug is roughly the amount of venom a bee carries around in its stinger.) These
doses were sublethal for most of the mice, but a few unlucky ones didn’t make
it past this stage. Of the ones that survived, the researchers nailed them
again three weeks later with a massive, lethal dose of bee venom, i.e., four
“stings” of 200 ug venom each. (See figure.)…